Positive working color proofing system comprising polyvinyl acetal/polyvinyl alcohol/polyvinyl acetate resin

ABSTRACT

This invention relates to positive working photosensitized sheet constructions which, upon exposure to an actinic radiation source through a screened image, can accurately reproduce said image. The construction is useful as a color proofing film which can be employed to predict the image quality from a lithographic printing process.

BACKGROUND OF THE INVENTION

In the graphic arts, it is desirable to produce a color proof to assista printer in correcting a set of photomasks which will be used inexposing printing plates. The proof should reproduce the color qualitythat will be obtained during the printing process. The proof must be aconsistent duplicate of the desired half tone or line image, and shouldneither gain nor lose color. Visual examination of a color proof shouldreveal the following characteristics:

1. Any defects on the photomask.

2. The best color rendition to be expected from press printing of thematerial.

3. The correct gradation of all colors and whether grays are neutral.

4. The need, if any, for subduing any of the colors and/or givingdirections for altering the film photomask before making the printingplates.

Color proofing sheets for multi-colored printing have heretofore beenmade by using a printing press proof which requires taking all the stepsnecessary for actual multicolor printing. Such a conventional method ofcolor proofing has been costly and time consuming. Alternate colorproofing methods have therefore been developed to simulate the qualityof press proofs. There are two known types of photographic colorproofing methods, namely, the surprint type and the overlay type.

In the overlay type of color proofing, an independent transparentplastic support is used for producing an image of each color separationfilm. A number of such supports carrying colored images are thensuperimposed upon each other and placed on a white sheet to produce acolor proof. The overlay type of color proofing method has thedisadvantage that the superimposed plastic supports tend to darken thecolor proofing sheet, and, as a result, the impression of the colorproofing sheet thus prepared becomes vastly different from copiesactually obtained by a conventional printing press proof. Its primaryadvantage is that it is quick and can serve as a progressive proof bycombining any two or more colors in register.

In the surprint type of color proofing method, a color proofing sheet isprepared by successively producing images of different colors fromdifferent color separation films onto a single receptor sheet. This isdone by utilizing a single opaque support and by applying toners,photosensitive solutions or coatings of photosensitive materials ofcorresponding colors on the opaque support in succession. An example ofthis approach is described in U.S. Pat. No. 3,671,236. An advantage ofthe surprint type of color proof is that the color saturation is notinfluenced by superimposed plastic supports. This method more closelyresembles the actual printing and eliminates the color distortioninherent in the overlay system.

Various processes for producing copies of an image embodyingphotopolymerization and thermal transfer techniques are known as shownin U.S. Pat. Nos. 3,060,023; 3,060,024; 3,060,025; 3,481,736; and3,607,264. In these processes, a photopolymerizable layer coated on asuitable support is imagewise exposed to a photographic transparency.The surface of the exposed layer is then pressed into contact with theimage receptive surface of a separate element and at least one of theelements is heated to a temperature above the transfer temperature ofthe unexposed portions of the layer. The two elements are thenseparated, whereby the thermally transferrable, unexposed, image areasof the composite transfer to the image receptive element. If the elementis not precolored, the tacky unexposed image may now be selectivelycolored with a desired toner. The colored matter preferentially adheresto the clear unpolymerized material. U.S. Pat. No. 3,574,049 provides atransfer process for printing a design on a final support whichcomprises (a) printing a design onto a temporary support, (b)superimposing the temporary support and the final support, (c) applyingheat and/or pressure to the superimposed structure formed in (b), and(d) separating the temporary support from the final support whichretains the printed design. The affinity of the design for the temporarysupport is lower than its affinity for the final support.

In U.S. Pat. No. 3,721,557 a method of transferring colored images isclaimed which provides a stripping layer coated between thephotosensitive element and the support. When the photosensitive layer isexposed to actinic light and developed, the more soluble portions areselectively removed to produce a visible image. The image-carryingsupport is pressed against a suitable adhesive coated receptor and,subsequently, the carrier support sheet is stripped to accomplish thetransfer of the image. A fresh layer of adhesive is applied to thereceptor for each subsequent transfer.

U.S. Pat. Nos. 4,260,673 and 4,093,464 describe positive workingone-piece proofing systems based on orthoquinone diazides. In U.S. Pat.4,093,464 a colored image is transferred to a receiver sheet afterexposure and development. U.S. Pat. 4,260,673 describes transfer of asolid color layer to a receiver sheet prior to exposure and development.U.S. Pat. No. 4,659,642 teaches a positive working color proofing systemwhich has a transparent substrate, a colored photosensitive layer on thesubstrate, and a top adhesive layer. The present invention improves uponthe foregoing by incorporating an improved positive working colorproofing film comprising a poly(vinyl acetal/vinyl alcohol/vinylacetate) terpolymer in the photosensitive layer.

SUMMARY OF THE INVENTION

The present invention provides an improved method for forming a coloredimage which comprises:

A. providing a photosensitive element which comprises, in order:

(i) a substrate having a release surface; and

(ii) a photosensitive layer on said release surface, whichphotosensitive layer comprises a light sensitive, positive working,naphthoquinone diazide compound; a resinous binder composition, whichcomposition contains at least 20% of a resin having the general formula

    --A--B--C--

wherein a plurality of each of components A, B and C occur in ordered orrandom sequence in the resin and wherein A is present in said resin atabout 5% to about 20% by weight and comprises groups of the formula##STR1## B is present in said resin at about 4% to about 30% by weightand comprises groups of the formula ##STR2## and C is present in saidresin at about 50% to about 91% by weight and comprises acetal groupsconsisting of groups of the formulae ##STR3## where R is lower alkyl orhydrogen, and wherein said group I. is present in component C from about75% to about 85%; group II. is present in component C from about 3% toabout 5%; and group III. is present in component C from about 10% toabout 22%; wherein all acetals are based on the mol number of components(C) and at least one colorant; and

(iii) an adhesive layer in direct contact with said photosensitivelayer, which adhesive layer comprises a polyvinyl acetate polymer andwhich adhesive layer is nontacky at room temperature, thermallyactivated and can be transferred at temperatures between 60° C. and 90°C.; and

B. either

(i) laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and removing saidsubstrate by the application of peeling forces; and imagewise exposingsaid photosensitive layer to actinic radiation; or

(ii) imagewise exposing said photosensitive layer to actinic radiation;and laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and removing saidsubstrate by the application of peeling forces; or

(iii) laminating said element with heat and pressure via said adhesivelayer to a developer resistant receiver sheet; and imagewise exposingsaid photosensitive layer to actinic radiation; and removing saidsubstrate by the application of peeling forces; and

C. removing the exposed areas of said photosensitive layer with asuitable liquid developer, which removing is conducted at a temperatureat which said adhesive layer is substantially non-tacky; and preferably

D. repeating steps A through C at least once whereby anotherphotosensitive element having at least one different colorant islaminated onto said receptor sheet over the non-removed portions of thepreviously laminated photosensitive layer or layers.

The invention also comprises the above described photosensitive element.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

In carrying out the method of the invention, one employs a photographicelement which broadly comprises a substrate having a release surface, acolored photosensitive layer on the release surface and an adhesivelayer on the photosensitive layer. Optional additional layers containinganti-halation materials, adhesion promoters or release agents may alsobe used.

In the preferred embodiment, the substrate is composed of adimensionally and chemically stable base material which does notsignificantly change its size, shape, or chemical properties as theresult of the heating, coating or other treatments which it mustundergo. One preferred material is polyethylene terephthalate. In theusual case it has a thickness of from about 1 to about 10 mils, a morepreferred thickness is from about 2-5 mils and most preferably fromabout 2-3 mils. Suitable films include Hostaphan 3000, available fromHoechst Celanese Corporation, Mylar D, available from DuPont and Melinexgrades 0; 052; 442; 516 and S, available from ICI. The surface of thesubstrate may be smooth or may be provided with a matte texture byvarious methods known in the art.

Matte films include Melinex 377 and 470 from ICI. These materials havethe unique property of giving the final image a desired matte finishwithout any extra steps. One can control the gloss of the final image byproperly selecting the matte finish of the temporary support. Thiseffect works because the top layer of the final image is originally incontact with this matte surface. This does not occur with a separaterelease layer between the temporary support and photosensitive layer. Anadditional advantage of coating on a matte surface is that subsequenttransferred layers generally adhere better to a rough surface than to asmooth surface.

A similar matte finish of the final image can be obtained by embossingthe shiny, top surface of the image with a matte material, such asdescribed above. This is done by laminating together the final image andmatte material under pressure and temperature. The matte material isthen generally removed after lamination. The advantage of this method isthat the finish of the final proof can be varied. Furthermore, thematting material can be used repeatedly.

A third method for producing a matte finish uses a heat transferablelayer, such as Butvar 90, available from Monsanto, coated onto a filmwith a rough surface, such as Melinex 329, available from ICI. Thetransferable layer is laminated to the final image under pressure andtemperature. Then the film with the rough surface is peeled off. Therough surface of the transferred layer imparts a matte finish to thefinal image. The advantage is that all layers appear matte and that theextra transferred layer protects the image. U.S. Pat. Nos. 4,294,909 and4,376,159, also suggests various methods for making a matte surface.

In either case, the substrate must have a release surface, that is, itmust be capable of releasably holding the photosensitive layer thereto.This may be accomplished either by the substrate surface beinginherently releasable, being rendered releasable by a suitable treatmentor being provided with a release layer over the substrate surface. Sucha release layer may comprise polyvinyl alcohol.

Releasably bonded to the release surface is the photosensitive layer.The photosensitive layer broadly comprises a photosensitizer, colorants,binding resins, and other optional ingredients such as plasticizers,acid stabilizers, surfactants, antistatic compositions, uv absorbers andresidual coating solvents.

The preferred photosensitizer is a light sensitive, naphthoquinonediazide. The most preferred photosensitizer is the ester ofbis-(3-benzoyl-4,5,6 trihydroxy phenyl)-methane and2-diazo-1-naphthol-5-sulfonic acid as taught in the U.S. Pat. No.4,407,926. Other suitable photosensitizers are taught in the U.S. Pat.Nos. 4,266,001, 3,106,365, 3,148,983 and 3,201,239. The diazo compoundsof choice are preferably soluble in organic solvents.

Suitable binding resins have the general formula

    --A--B--C--

wherein a plurality of each of components A, B and C occur in ordered orrandom sequence in the resin and wherein A is present in said resin atabout 5% to about 20% by weight and comprises groups of the formula##STR4## B is present in said resin at about 4% to about 30% by weightand comprises groups of the formula ##STR5## and C is present in saidresin at about 50% to about 91% by weight and comprises acetal groupsconsisting of groups of the formulae ##STR6## where R is lower alkyl orhydrogen, and wherein said group I. is present in component C from about75% to about 85%; group II. is present in component C from about 3% toabout 5%; and group III. is present in component C from about 10% toabout 22%. All of said acetal members are based on the mol number ofacetal units in component C. An important resin selection criterion isthat it must be a good firm former.

These resins are more fully described in U.S. Pat. No. 4,665,124 whichis incorporated herein by reference.

The colorants useful for the present invention include various classesof dyes and pigments. In the most preferred embodiment, pigments havingan average particle size diameter of about 1 micrometer or less areused.

Optional plasticizers which may be incorporated into the photosensitivelayer include those of the phthalate and phosphate types. Preferredplasticizers include dibutyl phthalate and dimethyl phthalate. Polymericplasticizers include acrylic resins such as Carboset 525 available fromBF Goodrich. Developing aids include polymers with acid groups such asCarboset XL27 available from BF Goodrich, Scripset 540 available fromMonsanto and Elvacite 2028 available from DuPont.

These ingredients may be blended with such compatible solvents as gammabutyrolactone, diacetone alcohol, propylene glycol monomethyl ether,ethanol, methyl cellosolve and methyl ethyl ketone, coated on therelease surface, and dried. In the preferred embodiment, thephotosensitive layer has a coating weight between approximately 0.1 and5.0 g/m². The most preferred weight is from about 0.4 to 2.0 g/m².

In the preferred embodiment, the photosensitizer is present in thephotosensitive layer in an amount of from about 15 to about 60 percentby weight; or more preferably from about 20 to about 50 percent byweight.

In the preferred embodiment, the colorant is present in thephotosensitive layer in an amount of from about 10 to about 40 percentby weight; or more preferably from about 13 to about 34 percent byweight.

In the preferred embodiment, the binding resin is present in thephotosensitive layer in an amount of from about 20 to about 75 parts byweight; or more preferably from about 30 to about 70 parts by weight.

In the preferred embodiment, the plasticizer, when one is used, ispresent in the photosensitive layer in an amount of up to about 20 partsby weight; or more preferably up to about 15 parts by weight and mostpreferably from about 12 to about 15 parts by weight.

Typical formulations for the photosensitive layer include:

    ______________________________________                                                       Yellow                                                                              Magenta  Cyan   Black                                    ______________________________________                                        propylene glycol monomethyl                                                                    57.00   50.40    33.72                                                                              43.44                                  ether                                                                         methyl ethyl ketone                                                                            9.37    10.72    34.22                                                                              25.20                                  gamma-butryolactone                                                                            19.35   22.53    16.96                                                                              15.33                                  diacetone alcohol                                                                              9.72    11.12    9.40 11.09                                  polyvinyl acetal/alcohol/                                                                      0.82    0.88     1.04 0.73                                   acetate resin in example #1                                                   Butvar B-90      0.36    0.41     0.45 0.42                                   Scripset 550     1.20    1.19     1.20 --                                     Scripset 540     --      --       --   1.41                                   Above diazo from U.S.                                                                          1.50    1.87     1.78 1.49                                   4,407,926                                                                     phthalo blue pigment                                                                           --      0.01     1.23 --                                     yellow pigment   0.68    0.02     --   --                                     magenta pigment  --      0.85     --   --                                     black pigment    --      --       --   0.89                                   ______________________________________                                    

The adhesive layer comprises polyvinyl acetate and may optionallycontain such other desired components as uv absorbers, opticalbrighteners, anti-static compositions and plasticizers. Useful polyvinylacetates non-exclusively include Mowilith DM-6, 20, DM-22, 25, 30 andmixtures thereof, available from Hoechst AG. These are usually dispersedin water, or dissolved in methyl isobutyl ketone or n-butyl acetate orother solvent compositions for coating on the photosensitive layer. Itis then dried to a coating weight of from about 5 to about 30 g/m², morepreferably from about 10 to about 20g/m². The layer may optionallycontain a uv absorber such as Uvinul D-50 from G.A.F. It may alsocontain a polymeric plasticizer such as Resoflex R-296, a polyesterplasticizer available from Cambridge Industries or Carboset 525available from BF Goodrich. It ma also contain antistats, such as Gafacand Gafstat from G.A.F. It may also contain other resins, such asNitrocellulose RS 1/2, available from Hercules. It may also contain anoptical brightener such as Uvitex OB from Ciba Geigy. The adhesive layershould not be tacky to the touch, during storage or during developmentof the photosensitive element. The layer should have a softening pointin the range of from about 60° C. to about 180° C., preferably 60° C. to120° C., more preferably 60° C. to 100° C. In the preferred embodiment,the polyvinyl acetate is present in the adhesive layer in an amount ofgreater than about 50 percent by weight. The plasticizer may be presentin an amount of up to about 30 percent by weight, the uv absorber up toabout 20 percent by weight, the optical brightener up to 1.0 percent byweight, and other resins up to about 50 percent by weight.

Typical adhesive formulations include:

    ______________________________________                                        I.         Water        50.00                                                            Mowilith DM-22                                                                             50.00                                                 II.        i-butyl acetate                                                                            78.00                                                            Resoflex     1.00                                                             Mowilith 30  21.00                                                 III.       i-butyl acetate                                                                            79.90                                                            Uvitex OB    0.10                                                             Mowilith 30  20.00                                                 ______________________________________                                    

In operation, the photosensitive element is laminated to a receptorsheet via the adhesive layer. The receiver sheet should be resistant toany adverse effects which may be caused by the developer of choice. Forexample, the receiver sheet should be water resistant if aqueousdevelopers are used. Plastic or plastic-coated receiver sheets areuseful for this purpose.

Useful receiver sheets include Melinex 329; 339; 994 and 3020 from ICI.Other white and nonwhite receiver sheets may also be used. Roughtextured and/or adhesion promoted surfaces are preferred for thereceiver, which must be able to withstand the laminating and developmentprocesses.

Lamination may be conducted by putting the receiver sheet in contactwith the adhesive side of the colored composite and then introducing thetwo materials into the nip of a pair of heated laminating rollers undersuitable pressure. Suitable laminating temperatures usually range fromabout 60° C. to about 90° C., preferably about 75° C. to about 85° C..After lamination, the substrate is peeled away, usually merely employingmanual peeling forces. The adhesive and photosensitive layers thusremain on the receiver sheet.

The photosensitive layer is imagewise exposed by means well known in theart either before or after lamination. Such exposure may be conducted byexposure to a uv light source through a photomask under vacuum frameconditions. Exposure may be performed with actinic light through aconventional positive flat. Exposures after lamination and peel apartare preferred for emulsion-to-emulsion contact. Mercury vapor dischargelamps are preferred over metal halide lamps. Filters may be used toreduce light scattering in the material.

After lamination, peel apart and exposure, the photosensitive layer isdeveloped by dissolving the exposed area in a suitable developer anddried. A suitable developer useful for developing a lithographicprinting plate made with the resin of the present invention includes anaqueous solution containing one or more of the following groups:

(a) a sodium, potassium or lithium salt of octyl, decyl, dodecyl, ortetradecyl monosulfate;

(b) a sodium, lithium, potassium or ammonium metasilicate salt,

(c) a lithium, potassium, sodium or ammonium borate salt;

(d) an aliphatic dicarboxylic acid, or sodium, potassium or ammoniumsalt thereof having from 2 to 6 carbon atoms; and

(e) mono, di-, or tri-sodium or potassium phosphate.

Other suitable developers include water, benzoic acid or sodium, lithiumand potassium benzoates and hydroxy substituted analogs thereof as wellas those developers desribed in U.S. Pat. No. 4,436,807. The adhesivelayer is not substantially removed by this development. Specificexamples of suitable developers non-exclusively include

    ______________________________________                                        I.                                                                            Water               95.0                                                      Sodium decyl sulphate                                                                             3.0                                                       Disodium phosphate  1.5                                                       Sodium metasilicate 0.5                                                       II.                                                                           Water               89.264                                                    Monosodium phosphate                                                                              0.269                                                     Trisodium phosphate 2.230                                                     Sodium tetradecyl sulfate                                                                         8.237                                                     ______________________________________                                    

Any developer solution which satisfactorily removes the exposed areas ofthe photosensitive layer after exposure while retaining the image areasmay be used. The selection of developer is well within the ability ofthe skilled artisan.

The process can then be repeated whereby another photosensitive elementhaving a different color is laminated to the same receiver sheet overthe previously formed image. In the usual case, four colored layers areemployed to produce a full color reproduction of a desired image. Theseare cyan, magenta, yellow and black.

The following non-limiting example serves to illustrate the invention.

EXAMPLE

The resin is made from a copolymer of polyvinyl alcohol/polyvinylacetate, Vinol 523. 75.0G of Vinol 523 which has from about 75% to 80%hydroxyl groups by weight and an average molecular weight of about70,000, is dissolved in a solution comprising 225.0 g of water and 200.0g of ethanol for 16 hours at 70° C. after which 10.13 of hydrochloricacid (37%) is added and the temperature adjusted to 60° C. while mixingvigorously. 37.66 g of propionaldehyde is slowly titrated into thereaction mixture. Simultaneously, 250.0 g of ethanol is likewisetitrated into the reaction mixture. The mixture is then neutralized to apH of 7.0 with a sodium carbonate/sodium hydroxide (50/50) mixture. Theproduct is isolated in granular form by precipitation with water. It isthen dried so as to have a moisture residue of not greater than 1.0%. Ayield of 107 g or about 96% is obtained. The average molecular weight isabout 90,000.

Using standard analytical techniques, the product is found to consist of13.6% acetate, 9.85% hydroxyl, and 76.6% acetal groups. Of the acetalgroups, 80% are found to be six-membered cyclic acetal, 4% arefive-membered cyclic acetal, and 16% are intermolecular acetals.

Four photosensitive solutions of cyan, yellow, magenta, and black areproduced according to the photosensitive formulations described above.The pigment is introduced as a dispersion of the above polyvinylacetal/alcohol/acetate resin and the appropriate pigment in a 1:1solvent mixture of gamma butryolactone and propylene glycol monomethylether. The pigment and resin loading in the dispersions are as follows:

    ______________________________________                                                Cyan Yellow      Magenta  Black                                       ______________________________________                                        Pigment   6.5%   5.0%        5.2%   5.5%                                      Binder    5.5%   6.0%        5.2%   4.5%                                      ______________________________________                                    

The solutions are coated and dried separately to the required opticaldensity onto 3 mil Melinex 516 polyester films as temporary support. Thesurface densities are roughly 0.8 g/m² for cyan, 0.9 g/m² for yellow,1.0 g/m² for magenta, and 1.3g/m2 for black. The adhesive solution, inparticular adhesive formulation number II from above, is coated on topof the photosensitive layers and dried to an surface density of 12 g/m².The yellow composite is then laminated at 80° C. with the adhesive sideonto either side of a 7 mil Melinex 3020 polyester receiver sheet. The516 temporary support is peeled away after lamination, leaving theadhesive and photosensitive layers on the receiver sheet. The yellowphotosensitive layer is then exposed to actinic light through aphotographic flat for the yellow color. The receiver sheet with theexposed yellow layer is then immersed for 15 sec in developer II fromabove at 27° C. with gentle pad rubbing on the photosensitive side. Theexposed yellow areas are thereby washed off and the nonexposed areasremain during development. The adhesive layer is not effected by thedeveloper. After this treatment, the imaged material is rinsed and thendried. The magenta composite is then laminated as before onto theimaged, yellow side of the receptor sheet. The temporary support isremoved as before. The magenta layer is then exposed through the magentaflat. It is then processed as with the yellow. The magenta is followedin a like manner by cyan and then by black to give a four color imagewhich is an accurate representation of the original from whichseparations are prepared.

What is claimed is:
 1. A method for forming a colored image whichcomprises:A. providing a photosensitive element which comprises, inorder:(i) a substrate having a release surface; and (ii) aphotosensitive layer on said release surface, which photosensitive layercomprises a light sensitive, positive working, naphthoquinone diazidecompound; a resinous binder composition which composition contains atleast 20% by weight of a resin having the general formula

    --A--B--C--

wherein a plurality of each of components A, B and C occur in ordered orrandom sequence in the resin and wherein A is present in said resin atabout 5% to about 20% by weight and comprises groups of the formula##STR7## B is present in said resin at about 4% to about 30% by weightand comprises groups of the formula ##STR8## and C is present in saidresin at about 50.% to about 91% by weight and comprises acetal groupsconsisting of groups of the formulae ##STR9## where R is lower alkyl orhydrogen, and wherein said group I. is present in component C from about75% to about 85%; group II. is present in component C from about 3% toabout 5%; and group III. is present in component C from about 10% toabout 22% wherein all acetals are based on the mol number of C unitspresent; and at least one colorant; and (iii) an adhesive layer indirect contact with said photosensitive layer, which adhesive layercomprises a polyvinyl acetate containing polymer and which adhesivelayer is nontacky at room temperature, thermally activated and can betransferred at temperatures between 60° C. and 90° C.; and B. either(i)laminating said element with heat and pressure via said adhesive layerto a developer resistant receiver sheet; and removing said substrate bythe application of peeling forces; and imagewise exposing saidphotosensitive layer to actinic radiation; or (ii) imagewise exposingsaid photosensitive layer to actinic radiation; and laminating saidelement with heat and pressure via said adhesive layer to a developerresistant receiver sheet; and removing said substrate by the applicationof peeling forces; or (iii) laminating said element with heat andpressure via said adhesive layer to a developer resistant receiversheet; and imagewise exposing said photosensitive layer to actinicradiation; and removing said substrate by the application of peelingforces; and C. removing the exposed areas of said photosensitive layerwith a suitable liquid developer, which removing is conducted at atemperature at which said adhesive layer is substantially nontacky. 2.The method of claim 1 wherein steps A through C are repeated at leastonce whereby another photosensitive element having at least onedifferent colorant is laminated onto said receptor sheet over thenon-removed portions of the previously laminated photosensitive layer orlayers.
 3. The method of claim 1 wherein said substrate comprisespolyethylene terepthalate.
 4. The method of claim 1 wherein saidsubstrate has a matte surface.
 5. The method of claim 1 wherein saidrelease surface on said substrate comprises polyvinyl alcohol.
 6. Themethod of claim 1 wherein said photosensitive layer comprises the esterof bis-(3-benzoyl-4,5,6 trihydroxyphenyl)-methane and2-diazo-1-naphthol-5-sulfonic acid.
 7. The method of claim 1 whereinsaid photosensitive layer further comprises one or more ingredientsselected from the group consisting of plasticizers, antistaticcompositions, uv absorbers and surfactants.
 8. The method of claim 1wherein the coating weight of the photosensitive layer ranges from about0.1 to about 5.0 g/m².
 9. The method of claim 1 wherein thephotosensitizer is present in the photosensitive layer in an amount offrom about 15 to about 60 percent by weight.
 10. The method of claim 1wherein the pigment is present in the photosensitive layer in an amountof from about 10 to about 40 percent by weight.
 11. The method of claim1 wherein the binding resin is present in the photosensitive layer in anamount of from about 20 to about 75 percent by weight.
 12. The method ofclaim 7 wherein the plasticizer is present in the photosensitive layerin an amount of up to about 20 percent by weight.
 13. The method ofclaim 1 wherein the adhesive layer has a coating weight of from about 5to about 30g/m².
 14. The method of claim 1 wherein the adhesive layerfurther comprises one or more ingredients selected from the groupconsisting of uv absorbers, anti-static compositions, resins,nitrocellulose, optical brighteners and plasticizers.
 15. The method ofclaim 1 wherein the polyvinyl acetate is present in the adhesive layerin an amount of at least about 50 percent by weight.
 16. The method ofclaim 14 wherein the uv absorber is present in the adhesive layer in anamount of up to about 30 percent by weight.
 17. The method of claim 14wherein the plasticizer is present in the adhesive layer in an amount ofup to about 20 percent by weight.
 18. The method of claim 1 wherein thelaminating step is conducted at a temperature of from about 60° C. toabout 90° C.
 19. The method of claim 1 wherein R is methyl.
 20. Themethod of claim 1 wherein R is ethyl.
 21. The method of claim 1 whereinthe A--B--C resin has a molecular weight of from about 5,000 to about100,000.
 22. A photosensitive element which comprises(i) a substratehaving a release surface; and (ii) a photosensitive layer on saidrelease surface, which photosensitive layer comprises a light sensitive,positive working, polymeric naphthoquinone diazide compound; a resinousbinder composition which composition contains at least 20% of a resinhaving the general formula

    --A--B--C--

wherein a plurality of each of components A, B and C occur in ordered orrandom sequence in the resin and wherein A is present in said resin atabout 5% to about 20% by weight and comprises groups of the formula##STR10## B is present in said resin at about 4% to about 30% by weightand comprises groups of the formula ##STR11## and C is present in saidresin at about 50% to about 91% by weight and comprises acetal groupsconsisting of groups of the formulae ##STR12## where R is lower alkyl orhydrogen, and wherein said group I. is present in component C from about75% to about 85%; group II. is present in component C from about 3% toabout 5%; and group III. is present in component C from about 10% toabout 22% wherein all acetals are based on the mol number of C unitspresent; and at least one colorant; and (iii) an adhesive layer on saidphotosensitive layer, comprises a polyvinyl acetate containing polymerand which adhesive layer is nontacky at room temperature, thermallyactivated and can be transferred at temperatures between 60° C. and 90°C..
 23. The element of claim 22 wherein said substrate comprisespolyethylene terepthalate.
 24. The element of claim 22 wherein saidsubstrate has a matte surface.
 25. The element of claim 22 wherein saidrelease surface on said substrate comprises polyvinyl alcohol.
 26. Theelement of claim 22 wherein said photosensitive layer comprises theester of bis-(3-benzoyl-4,5,6 trihydroxyphenyl)-methane and2-diazo-1-naphthol-5-sulfonic acid.
 27. The element of claim 22 whereinsaid photosensitive layer further comprises one or more ingredientsselected from the group consisting of plasticizers, acid stabilizers,antistatic compositions, uv absorbers and surfactants.
 28. The elementof claim 22 wherein the adhesive layer further comprises one or moreingredients selected from the group consisting of uv absorbers,anti-static compositions, resins, nitrocellulose optical brighteners,and plasticizers.
 29. The element of claim 22 wherein R is methyl orethyl and the A--B--C resin has a molecular weight of from about 5,000to about 100,000.